netdev - [PATCH net] net: fix possible overflow in __sk_mem_raise

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Message-Id: <20190212202627.184863-1-edumazet@google.com>
Date:   Tue, 12 Feb 2019 12:26:27 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH net] net: fix possible overflow in __sk_mem_raise_allocated()

With many active TCP sockets, fat TCP sockets could fool
__sk_mem_raise_allocated() thanks to an overflow.

They would increase their share of the memory, instead
of decreasing it.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/net/sock.h | 2 +-
 net/core/sock.c    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 2b229f7be8ebbc160706012f7ed03db85c5689d0..f43f935cb113b73c6fc0df35b5f43103ba131ab2 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1277,7 +1277,7 @@ static inline void sk_sockets_allocated_inc(struct sock *sk)
 	percpu_counter_inc(sk->sk_prot->sockets_allocated);
 }
 
-static inline int
+static inline u64
 sk_sockets_allocated_read_positive(struct sock *sk)
 {
 	return percpu_counter_read_positive(sk->sk_prot->sockets_allocated);
diff --git a/net/core/sock.c b/net/core/sock.c
index 6aa2e7e0b4fbdbc29d43d6b61a53b8de2a7ba269..bc3512f230a304c97c519a82c69d1e86f115b651 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2380,7 +2380,7 @@ int __sk_mem_raise_allocated(struct sock *sk, int size, int amt, int kind)
 	}
 
 	if (sk_has_memory_pressure(sk)) {
-		int alloc;
+		u64 alloc;
 
 		if (!sk_under_memory_pressure(sk))
 			return 1;
-- 
2.20.1.791.gb4d0f1c61a-goog